Automatic self sealing stem



July 8, 1958 I c, JOHNSON 2,842,336

AUTOMATIC SELF SEALING STEM Filed Aug. 22, 1955 v 3 Sheets-Sheet 1 I II 22 Char/e: /'T dab/7J0 INVENTOR.

- Filed Aug. 22, 1955 3 Sheets-Sheet 2 y 1958 c. F. JOHNSON 2,842,336

AUTOMATIC SELF SEALING STEM (bar/e5 f'f dofi/u 0/? IN VEN TOR.

July 8, 1958 c. F. JOHNSON 2,842,336

\ AUTOMATIC SELF SEALING STEM Filed Aug. 22, 1955 5 Sheets-Sheet 5 ATTORNEY AUTQMATIC SELF SEALING STEM Charles F. Johnson, Houston, Tex., assignor to George A. Butler, Houston, Tex.

Application August 22, 1955, Serial No. 529,740

1 Claim. or. 251-430 This invention pertains to automatic self-sealing stems, in particular to valve stems of valves adapted for high pressure service. The valves in which the invention will most often be used are rising stern gate valves, but the invention will also be useful in other types of valves including non-rising stem types.

One object of this invention is to provide a valve stem which will be automatically self sealing regardless of the pressure within the valve and regardless of the open or closed position of the stem.

Another object of this invention is to provide a stem sealing means which is simple yet effective.

Another object of the invention is to provide a stem and stem sealing means which can safely be dismantled under operating pressure for servicing and the like.

A further object of this invention is to provide a stem having separate closure means adapted to seal the stem when the stern closure is dismantled and the like.

A still further object of this invention is to provide a hydraulic stem sealing means automatic in operation, simple in manufacture, safe, and having interchangeable parts.

Other objects, uses, advantages, and improvements will be apparent from the specification, claim, and drawings, of which;

Figure 1 is a side elevation partly in vertical section of a preferred embodiment of the invention, the valve stem being in a substantially raised position;

Figure 2 is a vertical cross-sectional view of the embodiment of Figure 1, the valve stem being in a substantially lowered position;

Figure 3 is a side elevation partly in vertical section of a modified embodiment of the invention; and

Figure 4 is a horizontal cross-section taken at line 4-4 of Figure 3.

Referring in detail to the drawings in which the same reference numerals refer to the same parts wherever they occur, in Figures 1-2, valve body 11, bonnet 12, clamping ring 13, and stem 14 form a closure for valve chamber 15. The bonnet closure may be arranged in any suitable way otherwise than as'shown. Bonnet 12 has a shoulder 16 which fits into a recess 17 in body 11 and is sealed by resilient means 18 provided between shoulder 16 and recess 17. Clamping ring 13 overlaps bonnet 12 to hold bonnet 12 against body 11 and is screwed onto body 11 by suitable thread means on the ring and body or otherwise secured thereto. Bonnet 12 has a central longitudinal opening comprising an upper internally threaded portion 20, a central portion 21, a reduced annular portion 22, and an enlarged lower portion 23 having a downwardly diverging conical shaped connecting portion 24 with annular portion 22. Annular portion 22 has a small clearance wtih stem 14, which is received in the longitudinal opening of bonnet 12 and is threadingly received and held in place by a boss 25 which has a lower threaded portion 26 screwed into upper internally threaded portion States Patent 20 of bonnet 12. Hand-wheel 27 is held on an adapted portion 28 f stem 14 by a nut 29.

Bonnet 12 has'an injection port 53 below the threaded portion of upper portion 20, which is larger than central portion 21 of the longitudinal opening. Port 53 may be threaded to receive sealant injection equipment (not shown) and suitable plug means (not shown).

Stem 14 has an upper threaded portion 30 received in internal threaded portion 31 of boss 25, a lower threaded portion 32 to engage the valve gate means and an intermediate enlarged annular seat portion 36 which has an upper cone-shaped portion adapted to seat against the conical shaped portion 24 of lower portion 23 of the longitudinal bonnet opening. When stem 14 is rotated by handwheel 27 in a direction to cause upward movement of stem threads 30 in boss threads 31, the oppositely-pitched threads 32 at the lower end of the stem are screwed into a gate lifting nut means (not shown) so that the valve gate (not shown) will be moved upward at a faster rate than the stem, as will be apparent to those skilled in the art. Similarly, opposite stem rotation to lower the stem will cause the gate assembly to be moved downwardly at a faster rate than the stem.

, In the annular space between stem 14 and central portion 21 of the bonnet, a piston means 33 is disposed in sliding and sealing engagement with stem 14 and bonnet 12. The piston means 33 divides the longitudinal opening of bonnet 12 into upper and lower zones 34 and 35, respectively. Boss 25 has a lower diminished collar 60 which limits the upward movement of piston means 33.

Pressure in valve chamber 15 enters zone 35 past annular portion 22 and acts against the lower side of piston means 33. The pressure in valve chamber 15 will be 1 the same as the line pressure at the high pressure side of the valve gate for most types of gate valves. Sealant injected into zone 34 exerts a pressure against the upper side of piston means 33 and in addition seals about the engagements of piston means 33 with stem 14 and bonnet 12. The sealant in zone 34 is retained therein by piston means 33 and the closures at threads 20 and 26 and threads 30 and 31. The pressures in zones 34 and 35 will equalize by movement of piston means 33, zone 34 being substantially full of sealant so that the piston movement will not be excessive and so that sealant will be in contact with all of .the piston and threaded engagements to help seal them. When pressure in chamber 15 and zone 35 is decreased, piston means 33 will move downward somewhat as the sealant in zone 34 expands, but piston means 33 will not ordinarily drop to the bottom of zone 35.

When chamber 15 and zone 35 are under pressure, and stem 14 is rotated in opening or closing the valve, stem 14 will slide in the center opening in piston means 33, maintaining the seal. It is apparent that the seal about stem 14 will be maintained even though stem 14 be moved anywhere between the raised and lowered positions, Figures 1 and 2, respectively, since stem 14 will rotate in and slide through the piston means without disturbing the sealing efiect of the sealant in zone 34.

Should it be desired to open the sealing Zones 34 and 35 for inspection or for cleaning, stem 14 may be rotated to the fully raised position, threads 26 of boss 25 screwed out of threads 20 of bonnet 12, thereby bringing the cone-shaped surface of seat 36 into sealing engagement with conical surface 24 and forming a seal between chamber 15 and zone 35. Once this seal is established, nut 29, handwheel 27, boss 25, and piston means 33 may be removed. The pressure in chamber 15 will hold seat 36 against surface 24 while any of these parts are replaced or repaired.

A second embodiment of the invention is shown in Figures 3-4 of the drawings. Bonnet 40 has an axial longitudinal opening comprising an upper portion 41 and a lower portion 42, lower portion 42 being of larger internal diameter than upper portion 41, there being a cone-shaped portion 43 therebetween. Upper portion 41 has a threaded section 44 adapted to engage a threaded section 45 of a stem 46 which is received by the longitudinal opening of the bonnet. Stem 46 also has a lower threaded portion 47 adapted to enage the valve gate assembly (not shown). Lower portion 42 has a slot 49 adapted to receive a split ring 48 which encircles stem 46 leaving a clearance space 50 between the stem and the split ring. The position of the slot 4-9 and split ring 48 may be at any point spaced from the top of portion 42 of the longitudinal bonnet opening, leaving sufficient space between split ring 48 and cone-shaped portion 43 for a piston means 33. At the top of portion 42, a threaded injection port 51, having a section of smaller bore 52- at its entry into portion 42, is provided through the bonnet for injection of a sealant material into portion 42 above piston means 33. Port 51 is plugged by suitable means (not shown) when sealant is not being injected.

The embodiment of Figures 3-4 operates in the same manner as the embodiment of Figures 1-2 to form a seal around the stem 46. The sealant fluid above piston means 33 is retained by plug means in port 51, piston 33, and threads 44 and 45. Pressure in valve chamber 15 passes through clearance space 50 between split ring 48 and stem 46 and acts upwardly against piston means 33. Split ring 48 prevents piston means 33 from dropping out of portion 42 into chamber 15, and cone-shaped portion 43 limits the upward movement of piston means 33. There is no means in the embodiment of 'Figures 3-4 for access to the sealing elements without removing the bonnet. The embodiment of Figures 3-4 does not include a closure means such as is provided by seats 36 and 24 in the preferred embodiment.

While the invention is shown and described in connection with a rising stem gate valve, it can be used in non-rising stem valves as well. The invention may also be used in other types of equipment Where it is desired to seal a stem at its passage through a cover or wall of a pressure vessel or a vacuum vessel.

The sealant may be one of the types used in plastic sealed valves or it may be any other relatively high viscosity material. The sealant is usually at least somewhat fluid. The piston means may be any of the conventional types and may have ring seals or any other seals. Since piston means 33 is subjected to equal pressures from both sides, it may be of light construction. All of the sealing elements described may be made to be interchanged, and diiferent elements may be substituted. The arrangement of the elements is subject to considerable modification, as will be obvious to those skilled in the art. For example, seat element 36 may be made flat on top and made to seat against a flat bonnet surface, or a resilient seal may be substituted. Many other modifications are possible, and the scope of the invention is to be limited only as limited by the scope of the following claim.

I claim:

In a valve having a valve body adapted to contain a fluid under pressure, a bonnet closing one end of the body and having an axial bore provided at one end with threads, a rotatable valve stem having threads engaging the bonnet threads for moving the stem axially of said bore, the bore and the stern having spaced peripheries defining an interior chamber of annular cross-section, an annular piston disposed in said interior chamber dividing said chamber into an inner zone, freely communicating with said valve body and any pressured fluid therein, and an outer zone freely communicating with said threads, a body of fluid sealant under pressure in said outer chamber, said piston slidably engaging both said bore and said stem to assume a position in said chamber determined by the relative pressures in said zones and to accommodate rotational and axial displacement of said stem, relative to said bonnet, said bonnet having a I valve seat portion surrounding said stem intermediate said bore and the valve body, and an annular valve surface on said valve stem for seating engagement with said valve seat upon axial displacement of said valve stem.

References Cited in the file of this patent UNITED STATES PATENTS 1,149,848 Marsh Aug. 10, 1915 1,574,017 Beattie Feb. 23, 1926 2,444,868 Allen July 6, 1948 2,459,654 Kellogg Jan. 18, 1949 

